Radio range



Dec. 12, 1944. L. E. NORT0N 2,364,748

RADIO RANGE Filed April l, 1942 Snentor Lowell E'. Norton,

BH C@ M l Cittorneg Patented Dec. 12, 1944 RADIO RANGE Lowell E. Norton, Collingswood, N. J., assigner `to .Radio Corporation of America, a corporation of Delaware Application April 1 1942, Serial No. 437,149

2 Claims.

This invention relates to radio ranges, and more particularly to course and quadrant identii'ication in la four course simultaneous range. In U. S. Patent No. 2,314,795 granted to D. G. C. Luck on March 23, 1943, and entitled Radio ranges, systems of quadrant identification by means of phase reference modulation are described. Application Serial No. 436,430, led by D. G. C. Luck on March 27, 1942, and entitled Improvement in radio ranges describes a reference tone generator providing a tone definitely related in phase to the course tone but at an odd integral harmonic or subharmonic frequency. An object of the present invention is the provision of means for identifying the courses and quadrants of a radio range which radiates non-directionally a special reference tone in conjunction With the usual directional fields including interlocked A-N signals. Another object of the invention is the provision of a device for connection to the tone output of a mobile range receiver which will give a direct visual quadrant identification. A further object is the provision of a method of identifying the courses and quadrants of a four-course radio range.

The invention Will be described with reference to the accompanying drawing, of which Fig. 1 is a graph of a radio range pattern; Fig. 2A is a graph representing the voltages appearing in the output of a receiver operating in a positive range lobe, Fig. 2B is a similar representation of the voltages produced in a negative range lobe, Fig. 2C represents the voltages of Fig. 2B after one component has been acted upon by a phase shifter; and Fig. 3 is a circuit diagram of the device of the invention.

Referring to Fig. 1, the equisignal courses I, 2, 3 and 4 are indicated as the lines along which a receiver will pick up signals A and N with equal intensity from the range transmitter. The directive radiation patterns of the range antennas are illustrated as overlapping figures of eight with lobes of opposite polarites, arbitrarily designated as positive and negative. In the usual four course simultaneous range, a non-directional antenna is used to radiate a carrier which may be modulated with speech, or in the present instance, With a reference tone. The side bands, modulated at 1020 cycles per second. the so-called course tone, are directionally radiated by the range antennas and are keyed by interlocking signals A and N respectively as in-` dioated in Fig. 1. As described in the aforementioned application Serial No. 272,017, the nondirectional carrier may be modulated with a reference tone related in phase and frequency to the course tone for providing an indication to the operator of a receiving station of the course or quadrant in which the receiving station is located.

With a range set up for a reference tone of one-third the frequency of the course tone, the transmitter phases may be adjusted so that a course tone peak occurs simultaneously with a reference tone peak in the pattern lobes marked plus, while a course tone trough coincides with a reference tone peakin the lobes marked minus in Fig. 1. These relationships are illustrated in Figs. 2a, 2b and 2c, Where the course tone voltage is represented by the curve 5 and the reference tone voltage by the curve 1. Fig. 2a shows the voltages appearing in the output of a receiver in one of the positive lobes, While Fig. 2b shows the voltages in-the output of a'receiver in one of the negative lobes. It is apparent that the ratio of the peaks to the average value of the resultant Wave 9 is considerably higher in the positive quadrants than it is in the negative quadrants. In accordance with the invention, an indicator is actuated as a function of the ratio of the peak value to the average value of the complex range modulation.

Referring to Fig. 3 the output of a range receiver (not shown) is supplied to the primary Il of a transformer l5, which is provided with two secondary windings ll and I9. The secondary l1 is connected to a voltage divider 21 provided with taps 29 and- 3|. The tap 29 is connected through a capacitor 33 and a current limiting resistor 39 to the grid of a vacuum tube 4|. The capacity of the capacitorY 33 is so related to the resistance of the grid leak i5 that substantially no phase shift at the reference tone frequency is produced by the combination. The tap 3l of the voltage divider 2l is connected through a capacitor 35 and a current limiting resistor 31 to the grid of a second vacuum tube 43. The capacity of the capacitor 35 is so related to the resistance of the grid leak 41 that a phase shift of approximately is introduced in the reference tone Wave with respect to its unshifted phase, or with respect to a fixed reference suchl as the course tone wave,

The secondary I9 of the transformer l5 is connected to a double diode tube 2| in a full Wave rectifier circuit. The output of the rectifier 2| is delivered across a tapped resistor 23, which is connected to supply predetermined fractions of the rectified voltage to the grids of the tubes 4| and 43 in series with the voltages applied thereto from the secondary winding I7.

The anodes of the tubes 4| and 43 are connected to the control electrodes 53 and 5| respectively of a twin electron ray indicator tube 55 such as an RCA 6AF6-G. Anode potential is supplied to the tubes 4| and 43 from a source 51 through the load resistors 59 and 6| respectively, shunted by capacitors 63 and v|55. The target potential for the indicator tube 55 is also provided by the source 51.

The operation of the device is as follows: The

complex wave corresponding to the combined modulations of the range is rectified at 2| to produce a direct voltage proportional to the average value of the wave which may or may not be keyed, depending on whether the receiver is in an A, N, or on course position. A sufficient iraction of this voltage is applied to the grids of the tubes 4i and 43 through the resistors 39 and 41 as to bias the tubes beyond cut off to such an extent that a wave of the form shown in Fig. 2b will not have lpeaks sufliciently high to overcome the bias and allow either tube to conduct plate current. However, the circuit adjustment must be such that the peaks of a wave like that shown in Fig. 2a which has peaks higher than any part of that shown in Fig. 2b will overcome the bias and allow short pulsesof plate current to flow. The function of the phase shifting network 35,

l1 is to change the relationship between the two modulation components as shown in Fig. 2c, which represents the resultant of a wave like that of Fig. 2b' after it has been acted upon by the phase shifter. Comparison with Fig. 2a shows the shapes to be nearly the same. Thus the phase shifter changes a wave derived from the signal in a quadrant of one polarity to a wave having the shape of one derived from the signal in a quadrant of the opposite polarity. If the device is operating in a positive quadrant, the Fratio of peak t0 average value of the modulation will be relatively high, and the bias of the tube 4| will be overcome enough to allow short pulses of plate current to flow. These pulses are smoothed into a substantially constant voltage by the integration circuits including resistor 59, capacitcr 63, and resistor 6I and capacitor 65, keyed according tothe quadrant keying of the course tone. The electrode 53 of the indicator tube is energized by this voltage, causing the corresponding section of the fluorescent targetvto blink with the keying. the grid of the tube 43 is acted upon by the phase shifter 35, 41, it has a relatively low ratio of peak to average value, and the tube 43 remains cut off. Conversely, in a negative quadrant, the section of the target 55v controlled by the electrode 5| will blink with the course tone keying, while the section controlled by the electrode 53 will not. The indicator will be actuated in a similar manner when the receiver is on one of the courses deiined by the overlapping lobes,

along course I, the positive section of the indicator will be continuously actuated; along course 2 the -positive section will blink A and the negative section will blink N, and so on.

Thus the invention has been described as a device for connection to the output of a mobile range receive to give visual identification of the courses andquadrants of a four course simultaneous radio range which non-directionally radiates an auxiliary reference modulation. This is done by comparing the peak and average Values of the resultant modulation, and actuating indicators in accordance with their ratio.

I claim as my invention: v

l. In'a course andquadrant identification system for a four course simultaneous radio range, arranged to radiate directionally elds of one side band frequency and to radiate non-directionally a iield modulated at a frequency harmonically related to the modulation frequency corresponding to said side band, means for deriving from the resultant range signal an alternating current wave corresponding to the modulation of said range signal, rectifier means arranged to derive from said wave a potential proportional to the average amplitude thereof, two ampliers connected to said rectifier means and biased beyond cut-off by lsaid potential, means connected to apply said alternating current wave directly to the input of one of said amplifiers and through a phase-shifting network to the input of the other of said amplifiers, whereby one of said amplifiers operates when the ratio of the peak amplitude to the average amplitude of said alternating cur- 'rent wave exceeds a predetermined value, and

the other of said amplifiers operates when saidv` ratio is less than a predetermined value, and indicator means connected to the respective output Since the voltage applied to circuits of said amplifiers.

2. A deviceresponsive to the ratio of the peak amplitude to the average amplitude of a complex wave comprising two harmonically related components, including means for deriving from said wave a iirst potential proportional to the average amplitude thereof, means for deriving from said wave a second potential proportional to the peak amplitude thereof, means arranged to add said second potential to said rst potential and apply the sum to the control circuit of a i'lrst peak responsive device, means arranged to shift the phase of the lower frequency one of the harmonically related components of said complex wave with respect to the higher frequency component of said wave and to derive from the resultant wave a third potential proportional to the peak amplitude thereof, means arranged to add said third potential to said first potential and apply the 'sum to the control circuit of a second peak responsive device.

LOWELL E. NORTON. 

